Contact cards let you take quick action at that moment. Just click a purple contact and you’ll be presented with the options (if the email address is in black and not in a purple pill, click to Add to Contacts).
A few very handy features live on the Contact card:
Marking a contact as Important means all messages From or To that contact are added to your Important view, so if there’s a contact you want to keep close to click Important.
If you only want to quickly view the messages from a contact you can click the magnifying glass to search for all messages for that Contact.
Just as some contacts are very important, others may be less so. Where that’s the case you can mute them which will send any new messages received from that contact straight to Archive.